Telephone-transmitter.



PATENII'ED JULY 24, 1906.

E. E. CLEMENT. TELEPHONE TRANSMITTER.

APPLIGATION FILED MAY 17, 1904.

UNITED STATE PATENT OFFICE.

EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO THEDEAN ELEOTRIOCOMPANY, OF ELYRIA, OHIO,

A CORPORATION OF OHIO.

TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Patented July 2 1906.

Application filed May 17, 1904. Serial No. 208,339.

To (1,77 whom it mrty'concern:

' Be it known that I, EDWARD E. C EMENT, a citizen of the United States,residing at Washington, in the District of Columbia, have invented acertain new and useful Improvement in Telephone-Transmitters, of whichthe following is a specification, reference being had therein to theaccompanying drawings. o

My invention relates to telephone-transmitters, and particularly to thattype of granular transmitters commonly known as the solid back.Instruments of this type have two distinguishing characteristics, onebeing that the electrodes and the granular material between them areinclosed in a cup or chamber of small diameter as referred to the maindiaphragm "and the second being that the back electrode is solidly andrigidly supported. A third characteristic feature which was found in theoriginal solid-back instruments was that of having the .cup or chambercarried upon and integral with the support for the back electrode. Thelatest and best designs, however, do not'possess this feature, supportforv the chamber being either the bridge or the diaphragm indifferently,the principal point of identity in all being the rigid mounting of theback electrode.

My present invention oins featur es of both the early and the latedevices, in that while the back electrode is rigidly secured to thebridge the containing cup or chamber vibrates with the diaphragm,although not supported thereon. It is the ob'ect of my invention toeliminate oints of weakness and defects which have een shown to inherein the transmitters heretofore used and to produce an instrumentthatwill be economical to manufacture, convenient to assemble, and of a highand uniform efficiency.

A further object of my invention is to pro duce an instrument that shallbe articularly suitable for use on common atterycircuits. y

Apart from the consideration of resistance, the size of the chamber, andthe amount of filling, there are several points to be taken into accountin common battery-work that are immaterial where local-circuittransmitters only are in question. For instance, it is desirable thatexposed circuit-terminals should be avoided and'that the main circuitshould not be connected in any way with the frame or shell. If possible,connection to the movable electrode should be effected without goingthrough the diaphragm, andall connections should be solid andsubstantial, having ample current-carrying capacity to revent possibleburn-outs.

n order to obtain my objects, as will be noticed upon readin my detaileddescription, I have departed from convention in at least two standardparts-win, the diaphragm and the electrode-chamber. I find that thechanges I have made produce very marked results in the way of increasedvol ume of .transmission and much greater sensitiveness. A large part ofthis improvement I ascribe to my peculiar form of diaphragm. In almostall transmitters in use prior to my invention the diaphragm has een aflat circular piece of metal, formerly of iron and now usually ofaluminium, with each surface an unbroken plane. A rubber band is usuallystretched about its periphery for a double purp0sefirst, to insulate thediaphragm from the frame, and, second, to slightly com ress its edge,and thereby produce a buck e in the center to put it under tension.phragm free to vibrate, held but not clamped at the edges between thelimits of its amplitude of vibration, has a certain swing between whatmay be called the dead-points, there being neither compression nortension strains upon either skin. As the diaphra m swings one way drivenby the vibration o the voice it absorbs energy for its return swing, andalthough in a sense the speech vibrations directly assist it in thisreturn motion, yet it is rinci ally the stored energy that swings it ackom the'deadpoints and to its forward limits. The main losses in thediaphragm motion are those due to inertia and air resistance, and theseproduce their maxi mum retarding effect during the swing between thedeadoints.

Without having stated the problem in the I It should be stated that adiaare then formed up into a circular flange or stem passing through thebridge of the transin the way of putting the diaphragm under result thatthe damping effect usually lowers the efficiency of the instrument morethan the tensional arrangement has raised it. I have found that the sameor a better result tension or stiffening it may be attained Without anyexcessive damping, and this by means inhering in the diaphragm itself,so that subsequent to its manufacture no further adjustment is requiredthan that ordinarily-given in assembling. I take my diaphragm, which ispreferably of aluminium, and in the center thereof produce'an a erturenot quite large enough to admitthe ody of the cup or resistance-chamberI propose using. I then subject the diaphragm to a process of forming,during which the metal is preferably worked toward the center toslightly and uniformlythicken the edges around the central aperture.These edges collar upstanding from and substantially perpendicular tothe plane of the diaphragm.

n so forming up the edges they are expand-' ed, and thereby againreduced in thickness, the diameter of the central aperture'being at thesame time increased until it is large enough to admit theresistance-chamber. This cup or chamber is afterward introduced upon theflanged side of the diaphragm, so that the edges of the flange restagainst a shoulder or flange upon the cup, and the bot-- tom of the cuplies flush with the outer face of the diaphragm. In assembling' the cupis maintained in this position by a supportingmitter and ispressedagainst the diaphragm by suitable springs, which serve to someextent as dampers and also to complete the elec trode-circuit.

My electrode chamber or cup differs from those usually employed, in thatit contains but one electrode, the bottom I of the cup itself serving asthe other. Saving thus the thickness of an electrode-plate andits carbonface in the depth of my chamber, I also gain in another wayviz., byrendering the body of the cup or chamber more sensitive as an auxiliaryto the main diaphragm, and that in the central position, where theamplitude of vibration is always the greatest.

In order to keep the main circuit entirely se arate from the frame orshell of the transmltter, I insulate one side of the electrodecircuit,as usual, by springing a rubber band around the edge of the diaphragm,and the otherside I protect by completing the connections through thesprings already referred to, mounting these springs on an insulatedpost, and by insulating with rubber or mica the metal collar or bosswhich receives the stud of the back electrode.

My invention is fully illustrated in the accompanying drawings, .whereinFigure 1 1s a sectional View of a transmltter 1 embodying my design.Fig. 2 is a rear view thereof with the shell removed. Fig. 3 is a detailview of the front side of the bridge, the latter being removed from thetransmitter to show the insulated contact-spring and theresistance-button.

Referring to the drawings,.A is a circular" frame or front plate flangedupon its rear side, provided with a bearing-face a for the diaphragm Dand recessed as usual over the diaphragm at a. Seated upon this face isthe diaphragm D, which I will presently describe, and reaching acrossthis diaphragm, somewhat to the rear thereof, lies the bridge B, securedat its extremities to opposite sides of the front plate by the screws 1)b. I have shown this bridge as a finished casting; but it mayconveniently be punched and formed out of sheet metal of considerablethickness. At its middle point the bridge is perforated with an opening6 through which extends with ample clearance the boss or collar on theplate 12*. This plate is solidly secured tothe bridge by means of thebushed screws 6 tapped thereinto. A. sheet of hard rubber, mica, orother suitable material m insulates the plate I) from the bridge.

The diaphragm D, as I have already stated, is centrally perforated at d,and the edges around the aperture are formed up into a flange or collar(1. Around the periphery of the diaphragm a rubber band or gasket (1 issprung, and the usual side springs 01 extend out from the flanges of thefront plate, with their sleeved extremities resting on the rubber gasketto hold the diaphragm in place.

Within the aperture of the diaphragm, with its bottom .flush with thefront face thereof, lies the cup C, containing the resistance-varyingelements of the transmitter. This comprises the thin li ht metal body 0,provided with an annular flange or shoulder 0, upon which rests the micaauxiliary diaphragm F, clamped to the cup around its edge by thethreaded ring f. This mica diaphragm or disk F is centrally perforatedto receive the stem e of the electrode-plate E, which passes through thetwin clampingplate e and the hollow stud e receiving the nut e outsidethe end thereof, by which the parts are drawn together to clamp the micadisk firmly between them. The stud e lies in the aperture in the collarb 'b and when adjusted therein is securely held by the setscrew 3.(Shown in Fig. 2.)

The electrode E is carbon-faced and of course in the operation of theinstrument remains fixed, inasmuchas it is supported upon the bridge B.The op osing electrode is the bottom of the cup itsel (indicated at 0and this I plate with gold in order to insure a high and uniformconductivity Without danger of deterioration. Granular carbon e isintroducedwithin the chamber, and as the electrode E is of a smallerdiameter than the chamber it constitutes apiston, leaving space forexpansion all around it.

circuitv ,thrreto, I, springs'P, supported'on the bridge and securedthereto by the screw-bolt 1), which is insulated by suitable bushingsand by an ex tension of the same plate which underlies the collar b; Thesprings P are formed from one integral piece of spring metal in substantial U shape, the bolt 12 passing through the horizontal connectingmember. The extremities of the springs straddle and rest upon theopposite edges of the threaded ring f, which being metallicallyconnected with the top of the cup- 0 completes the circuit from thesprings thereto. This arrangement is clearly shown in Fig. 3.

The electrode-circuit completed extends from the screw-post 1) throughthe springs P to screw-ring flange 0, cup 0, inner face 0 through thegranular carbon to electrode E, through stems e and stud e to the collarand boss b 1). Thus the current-carrying circuit is absolutely distinctfrom the shell or frame of the instrument.

The operation ofmyv transmitter is sufficiently apparent from thedescription; but I may note that vibrations due to soundwaves are not byany means limited to the diaphragm. It is quite true that this vibratesand by the pressure of its flange against the flange c of the cupvibrates the latter and thereby communicates more or less pressure tothe granular carbon; but it is also true that the cup 0 vibrates ofitself, and this not only as a whole, but also probably in the sense ofbending and distorting its bottom. All the effects thus producedreinforce each other, and the inner flange around the opening in thediaphragm insures a condition of constant tension in the latter whicheliminates the dead point or points from consideration.

It should be noted that I have shown the cup 0 lined as to its sidewalls with pa er 0 This is not absolutely essential; but I nd itadvisable, insuringthat the current-path between the electrodes shallbeconstant in length.

Having thus described my invention, what I claim, and desire to secureby Letters Pat- I cut, is-

1. In a telephone-transmitter a sup orting frame or plate, a diaphragmcarried t ereon, a central aperture being produced in said diaphragm, aresistance cup orchamber independently supported within said aperturewith its outer face substantially flush with the outer face of thediaphragm, and direct connection between said diaphragm and cup, anelectrode extending into said cup and rig- I: provide the contactidlyheld with respect thereto, substantially as described. 2. In a.telephone-transmitter a supporting frame or plate, a diaphragm restingthereon, said diaphra m being centrally'apertured and having its edgesaround the aperture formed up into an annular flange, a cup or chamberfitting within the aperture and supported against said flange, anelectrode within and vibrating" with the cup and the diaphragm, apiston-electrode extending into the cup or chamber and rigidly supportedwith respect thereto, together with granular carbon in said chamber, andmeans to complete a circuit therethrough, substantially as described.

3.. In a telephone-transmitter a supporting frame or plate, a diaphragmresting thereon, said diaphragm being centrally apertured and having itsedges around the apertures formed up into an annular flange, a flangedcup having its body within the aperture and its flange against thediaphragm-flange, an electrode within and vibrating with the cup, asecond electrode rigidly supported with respect to the first andextending into the cup, an auxiliary diaphragm extending about saidsecond electrode and clasping the mouth of the cup, and granularmaterial between the electrodes, substantially as described.

4. In a telephone transmitter, a diaphragm, an annular flange formed insaid diaphragm, an electrode independently supported so as to bevibrated y said flange, and a second electrode rigidly fixed withrespect to the first, substantially as described.

5. In a telephone transmitter, a diaphra m, a flanged aperture therein,a flanged cup, ying in the aperture withits bottom flush with the faceof the diaphra m, an electrode fixed in the cup, a second e ectrodeenterin the same but separately supported, a suppi ement'al diaphragmconnected to said second electrode and clamped around its edges to theperiphery of the cup, and granular material in the cup, substantially asdescribed.

6. In a telephone-transmitter, a diaphragm formed with an annularflange, an electrode separate from but 1 ing within said flange,unsupported there y, and vibrating with the diaphragm, a secondelectrode fixed with respect to the first, granular carbon between theelectrodes, and means to confine the same, substantially as described.

7. A diaphragm for acoustic instruments provided with a stiffening ribor flange having its outer edge open and disconnected.

8. A-diaphragni for acoustic instruments provided with an open annularstiffening flange or rib.

9. A diaphragm for acoustic instruments provided with an aperture and astiffeningflange havinglits outer edge open and disconnected.

10. A diaphragm for acoustioinstruments provided with an annularstiffening-flange IO provided with an aperture surrounded by a fdefining the Walls of a hole, said stiffeningstiifening-flan 6, saidflange having its outer i flange adapted to move an electrode. edge openan disconnected. In testimony whereof I have affixed my 5 11. A soundin-diaphragm for acoustic insignature in presence of two Witnesses.

struments provided with a central aperture EDWARD E. CLEMENT. having itsedges formed up into a stiffeningfiange, substantially as described.

12. A diaphragm for acoustic instrl-lments 'i tnesses: H

'Inmus DURAN'I, G. NICPARLA N.

